Xenapi shutdown should return True if vm is shutdown

clean and hard shutdown vm methods return a False if the vm
is currently shutdown. It should return a True, so that its
return value can be used to determine if the vm is shutdown
or not.

Fixes: bug #1195587
Change-Id: I758c43d45b15c3ef231e9eee3ecac620a44db824
Disassociate fixed IPs not known to dnsmasq

Currently, fix_ip disassociation only happens in release_fixed_ip(),
which is called by dhcp-bridge script when ip is released. But there
are circumstances when instancs fail to get lease from dnsmasq(instances
fail to boot or instances fail to spawn). In such case, DHCPRELEASE
packet sent to dnsmasq would never trigger dhcp-bridge to run. Thus the
fixed ip would not be disassociated from instance until
_disassociate_stale_fixed_ips() begins to run.

Actually, this patch borrows the idea from Vishvananda's
3f6739e2a8acdf20d01c0b5039a33f26d879587b commit: explicitly disassociate
fixed ip which is not known to dnsmasq, instead of via the dhcp-release
script.

Steps to reproduce:
1. Create an instance which doesn't send dhcp request to dnsmasq.
2. Delete the instance.
3. The fixed ip associated with the instance is not returned to pool.

Bug 1180766

Change-Id: Icc022ea2fb7af08fb7354e3a49c77ad5ae58f34c
Port extended-server-attributes API into v3 part2

Ports the extended-server-attributes extension and the corresponding
unittests to the v3 framework.

Partially implements blueprint nova-v3-api

Change-Id: I33e227de0e4d3e1e5f52ca79157e3846a0e6ee13
Ensure flake8 tests run on all api code

We need to exclude the plugins/xenserver directory
because the python2.4 code can't use as in except clauses.
The existing exclude directory accidentally included some
code in nova/api/openstack/compute/plugins and the related
tests. This code is now included in the flake8 tests,
and the current violations have been fixed up.

Fixes bug 1197858

Change-Id: Ib5f1b65d5d793f0f5854e898ca3ce751e43ef233
Merge "Xenapi shutdown should return True if vm is shutdown"
Merge "Disassociate fixed IPs not known to dnsmasq"
Merge "Ensure flake8 tests run on all api code"
Merge "Port extended-server-attributes API into v3 part2"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp